Propeller



Nov. 8, 1932. F. a. MARTENS ET AL r 1,836,391

PROPELLER Filed July 21, 1950 2 Sheets-Sheet l MKM v 0% @ZZZW NOV. 8,1932. J E ET AL 1,886,891

PQ PELLER Filed giil 21, 1930 v 2 Sheets-Sheet 2 Patented Nov. 8, 1932UNITED STATES PATENT OFFICE FREDERICK J. MABTENS AND CLINTON O.THOMPSON, OI MILWAUKEE, WISCONSIN PROPELLEB Application filed. July 21,1930. Serial No. 469,531.

' most efficient use of the propel or for take-off,

landing, etc.

Another important object of our invention is the provision of hydraulicmeans for changing the pitch angle of the blades, so as to insure thesmooth operation of the blades A still further object of our inventionis to provide a propeller having novel form of blades with novel meansfor changing the pitch angle of the blades whereby the combination ofthe formation of the blades and the means for changingthe pitch anglethereof to suit varying conditions will result in the production of apropeller of a highly efiicient type, capable for all aeronauticalpuroses.

A still further object of our invention is to provide .an improvedpropeller of the above character, which will be durable and eflicient inuse, one that will be simple and easy to manufacture and one which canbe placed upon the market and incorporated with an aeroplane at'a smallcost;

With these and other objects in View the invention consists in the novelconstruction,

arrangement and formation of parts, as will be hereinafter morespecifically described,

claimed and illustrated in the accompanying drawings; in which drawings:

Figure 1 is a front elevation of our im proved propeller, one section ofthe hub being removed to illustrate the mounting of the propeller bladesin the hub.

Figure 2 is a plan view of the improved propeller.

Figure 3 is a detail section taken on line 3-3 of Figure 2 looking inthe direction of the arrows and illustrating the means for changing theangle pitch of the blades.

Figure 4 is a diagrammatic view illustrating the hydraulic meansemployed for changing the angle pitch of the blades.

Figure 5 is a transverse section through one the of the propeller bladestaken on the line 55 of Figure 1.

Figure 6 is a transverse section taken through the propeller blade onthe line 6-6 of Figure 1.

Figure 7 is a view similar to Figure 3 showing a modified form of thehub.

Figure 8 is a detail section taken on the line 8-8 of Figure 7 lookingin the direction of the arrows and illustrating the means employed formounting the propeller blades in the modified form of hub.

Referring to the drawings in detail, wherein similar referencecharacters designate corresponding parts throughout the several views,the letter A generally indicates our improved propeller which comprisesa hub 10 keyed or secured in any other desired way for rotation with adrive shaft 11. The drive shaft 11 may be considered in the presentinstance as the crank shaft of the internal combustion engine of anaeroplane.

In that form of the invention, as illustrated in Figures 1, 2 and 3, thehub 10 comprises a pair of companion sections 11 and 12, securedtogether by the use of bolts 13 or other suitable fastening elements.The sections 11' and 12 are so constructed when placed and securedtogether to form a pair of parallel cylinders 14 arran ed on opposite.sides of the hub sleeve 15 which receives the engine shaft 11. In thepresent instance wehave shown two cylinders as the propeller is of thetwo-bladed type, but it is to be understood that more than two cylinderscan be rovided if a three or four bladed dpropeller is to be used. It isto be also note that the c linders are arran d substantially tan ny geli ub of the engine shaft 11 is the blade adjusting sleeve 17 havingformed on its inner end a rack 18 for a pur ose, which will be laterdescribed. The rac teeth are ofannular construction and are arran edwithin the hub. The inner end of the adjusting sleeve 17 is providedwith spaced collars 19, for a purpose which will also be-described.

The propeller blades 20 are of novel con- I struction and form; and eachembody a hub boss 21 rotatably received within its cylinder 14. Thebosses 21 and the cylinders are suitably grooved for receivinganti-friction bearings 22 and a thrust bearing 23 can be interposedbetween the inner ends of the cylinders and the bosses 21. The outerends of the bosses 21 carry discs 24 which abut against the outer facesof the cylinders as c early shown in Figures 1 and 2. The root of eachpropeller blade 20 at the boss end thereof embodies two stems or bladesections 25 which are formed on the opposite sides of the boss discs orflanges 24. These stems or blade sections 25 gradually converge towardone another in overlapping relation and termi nate in a single blade tip26.

laying out the new propeller blade design, the natural ggometrical pitchlead or helixis used in ma 'ng a uniform propeller, but in addition arigid structure is presented giving great strength and reinforcing themore delicate form 'of construction. This rigid structureis moreefiective eometrically and an effective lead is obtainetf by duplicatmgor doubling the propeller air-foil to produce a more eflicient, usefuldynamic reaction. In vertical position the distance of the stems oftheair-foil or blade sections 25 is overned by the true and effective gapor lstance between the blades for the most eflicient dynamic action.

s clearly shown in Figures 1 and 2, the

two air-foil portions or blade sections 25- continue from the rootordisc on the radius line to the standard nominal pitch line or abouttwo-thirds of the radius, finally of which they converge into a singleair-foil and continue as a sing e unit air-foil to the tip. It can bereadily seen that in this construction, the projected efl'ective proller area is greater on the blade face and lade back siderably, i. e.,the thickness of the a r foil of the two blade sections 25 and alsoatthe root would be less. This also would effect the remaining singleportion or tip 26. The minimum camber of the air foil in effective dragbeing overcome by the changeable an le of incidence due to theadjustment of the lades and reduced resistance drag. Due to theeffective pitch area, it will be noted that a propeller of lesser discarea may be used. An important dynamic factor lies in the fact that thecenter of pressure on the blade face will cause little or no flexing andwill be equalized throughout the blade area regardless of the air foilangle of incidence.

As to the angle of incidence of the trailing (lower) airfoil or bladesection 25 it may or may not be made greater. 1

The bosses 21 of the propeller blades are provided with pinion teeth 30which mesh with the rack 18, at the opposite sides thereof, formed onthe adjusting sleeve 17.

It is obvious that by shifting the adjusting sleeve 17 longitudinal ofthe engine shaft 11 that the blades can beturned about their axis forchanging the angle ofv pitch to suit varying conditions. 7

As best shown in Fi ures 5 and 6, the blade sections 25 and winge tipportions 26 are of true stream line formation in cross section, whichproduces the most efiicient dynamic thrust, as has been established byactual tests.

It has also been found that because of the resulting advantages, thisfeature of construction is equally applicable to any air-foil, and itis, therefore, to be understood that the inventionis not limited topropeller blades. It will be noted that the blade members are rotatableupon axis offset with relation to the axis of the propeller shaft 11,which is the normal center line of the blade tips 26. Obviously, as theblades are rotated to increase the cord width, the overall or winged tipdiameter of the blades is proportionately decreased, although in a muchlesser degree. This is due to the fact that each winged tip has arotative action, which varies the center line of the tip with relationto the axis of the propeller shaft, thus causing the tips to approach orrecede from a diametrical line passing through the axis of the propellershaft, the effect of which is to increase or decrease the overalldiameter.

It is believed that the advantages of the Y foregoing will be quiteapparent, in that the blades.

Any desired means can be utilized for shifting the adjusting sleevelongitudinally of the shaft, but we prefer to provide an hydraulic meansfor this purpose and the means provided forms an important part of mypresent invention. The chief advantage in using my hydraulic means forthe purpose of shifting the pitch angle of the blades, is that, due tothe mechanical method of the rack and pinion portions of the blade hubsit is not necessary to have an oscillation of more than one half to oneand one half inches even on the largest diameter of propeller and alsothat this method can be used efficiently and in a simple manner onmulti-motored planes.

This hydraulic means comprises an operating lever 31 pivoted at one end,as of 32, to a rigid part of the aeroplane or engine, such as the crankcase of the engine. This operating lever 31 intermediate its ends isprovided with a shift yoke 33 for engaging the shift collars 19 on theadjusted sleeve 17. The opposite end of the operating lever 31 from itspivot point 32 is pivotally connected as at 34 to the piston rod 35 of adouble acting piston 36. This double acting piston 36 is reciprocallymounted ina pressure cylinder 37, as clearly shown in Figure 4 of thedrawings. The piston 36 is normally mounted intermediate the ends of thepressure cylinder 37 and the opposite ends of the cylinder 37 havecommunicating therewith pressure feed pipes 38 and 39 respectively.These pressure feed pipes 38 and 39 communicate with the opposite endsof an operating cylinder 40, preferably arranged within the cock-pit ofthe aeroplane (not shown).

Reciprocally mounted within the operating cylinder 40 is an operatingpiston 41 which is normally arranged between the opposite ends of thecylinder. A piston rod 42 is connected with the piston 41 and extendsout of one end of the cylinder 40 through a suitable stuffing box. Asuitable bracket 43 having a segmental rack bar 44 formed thereon iscarried by the mentioned end of the cylinder and one side of the brackethas pivotally connected thereto a hand lever 45. The hand lever 45intermediate its ends has pivotally secured thereto the piston rod 42.For cooperation with the segmental rack bar 44, the hand lever 45carries a finger grip operated locking dog 46. By this construction theposition of the piston 41 can be controlled and locked againstaccidental movement.

We also provide an equalizing cylinder 47 and this cylinder hascommunication with one end thereof, the equalizing pipes 48 and 49 whichcommunicate respectively with the pressure pipes 38 and 39.

A spring pressed piston 50 is arranged within the cylinder 47 andnormally creates pressure on the fluid in the system, it beingunderstood that the various cylinders and pipes are filledwith asuitable fluid such as oil. i

By this construction when the piston-.41

J is manually operated, the fluid will be forced from the end thereof,according to the direction of movement of the piston and this fluidsleeve 17.

. It is obvious from the foregoing that a simple and effective means hasbeen provided for manipulatingthe said adjusting sleeve.

Referring to Figures 7 and 8, wherein the preferred form of the hubstructure is illustrated, the samelis of a one-piece' construction,either forgedor cast; The outer ends 'ofthe cylinders 10 being open" andprovided at their outer and inner. ends with enlarged bearing chambers51. i

The blade bosses 20 areinserted in the cylinder and thrust anti-frictionbearings 52 are placedin the chambers 51-. One of the anti-frictionbearings resting-against the boss flanges of the blades and the otherbearing against a holding plate 53 placed upon a reduced stud 54 carriedby the end of each blade boss. The plates 53 are of such a diameter asto bear against the cylinder ends.-

Suitable lock nuts 55 are threaded on the studs 54 into engagement withthe plates 53. Thus, it will be seen that an extremely simple, durableand economical structure has been provided,=which lends itself to simplemach1n1ng operatlons and insures closeness of fit and alignment, as wellas materially reducing the manufacturing costs.

Our propeller and the means employed for shifting the angle of pitch ofthe bladeshas' many noteworthy advantages over the propeller nowcommonly used, and an aircraft engine with a propeller of our type willgive steady divergence through its various speeds, resulting in completestaple oscillation and the consistent units of the changeable bladeangles of attack and placement thereof will go for propulsiveefiiciency.

Aside from the mechanical design and efficienoy of the propeller asshown, advantage is derived in aviation as follows: First, ground;second, taking off; third, free flight 5 fourth, ceiling; and fifth,landing.

First, ground, the advantage of the propeller on the ground is that thepropeller blades can be set at zero thrust thereby doing away with theblocking or holding of the aeroplane wheels. This condition of zerothrust would also give a zero torque, resulting in a perfectly freerunning engine.

Further the warming up process of the engine would be cut down to aminimum due to no inflow or slip stream upon the engine.

Second, at taking off, the angle of the blades can be set for giving thegreatest amount of ?spee(l.-.and pull thereby resulting. in .permittingof a quick take ofi to be had. The ordiznany propel1er'now .in use; withfixed pitch is adapted and liinitedto the: prerascertained rating of zP.of .motor, revolutions per uninute, plane pay :load .etc., 1 in :takingoff.

With our 1propeller,.:the adjustable vcontrollableapitch, beingmadezwhile in flight, the take-off can be *made ifrom. a; small fieldeat .a: lead angle :correct forithe 1H. 1 plane load, etc., or in otherwords the pilohmay rproduce rth'e :most .efiicient propeller thrust a tomeet the condition to take ofi his plane into freeflight; irregardlessof wind, LH. 1

5 5 erevolutions .perrminute and. load.

.Third,.'in,-free flighty'the correct angle of incidence can be made by.thezpilot to obtain the greatest air .speed'without efl'eoting theengine. :Itisifoundithabthere is a change of approximately-v fifty to.'.sixty revolutions per -minute.-f0r ;each degree of *movement for theblades. :Thisholds, good for either an increase or decrease: of :speed,:therefore the propeller can be .used 1 ion different en- ,.gines bycontrolling thepitch to suit the Y speed -land: power of each, While inflight.

:Fourth,-the propeller-blades-can be ad- ;justed for the ceiling, inother words'the angle ofthe blades can be changed to accord 3o withtheconditions ofthe atmosphere.

Fifth, in landing, ithas been demonstrated :that a, plane with a verylowlead angle, the .propeller undermotor power tends to stabilize andapproach the landing speed slower.

- 5 This is givenwiththepropeller described.

7 Changes in. details :may be made; without departing-from thespiritbrflscope of this invention :but what we claim as new is1..-A.propeller..blade comprising a disc- 40 shape'd-fiange,-body.portions projecting from one-face of the flangeat opposite sidesthereof, and asingle connecting tip, said body portions "partiallyoverlying one another through their entire lengths.

1'45 2. A ,propeller blade comprising spaced body sections and a singleconnecting tip,

said. body portions and tip being gradually tapered in crosssection fromtheir leading edges to their trailing edges, said body 50 portionspartially overlying one another throughout their entire lengths, the tipextending in the same direction as the body portions.

In testimony that We claim-the foregoing do We have hereunto set ourhands at Milwaukee, in'the county of Milwaukee and State of Wisconsin.

FREDERICK J. MARTENS.

CLINTON O. THOMPSON.

